alex anderson



Feb. 3, 1931. E. F. w. ALEXANDERS'ON 1,790,646

RADIO SIGNALING SYSTEM Filed May 9, 1925 '4 Sheets-Sheet 1 Inventor": Ernst FW- Alexanderson,

' His Attorney.

Feb. 3, 1931. E. F. w. ALEXANDERSON RADIO S IGNALING SYSTEM Filed May. 9, 1925 4 Sheets-Sheet 2 2% f mn Sm tm .A T VA I mW 3, 1931- E. F. WIALEXANDERSON RADIO SIGNALING SYSTEM Filed May 9, 1925 4 Sheets-Sheet 3 Irv/enter, Ernst T". 7\|ex 2molerson His AU;

or may 1931- E. F. w. ALEXANDERSON RADIO SIGNALING SYSTEM Filed May 9. 1925 4 Sheet-Sheet 4 .fl w Mvw s w 3w ..d, i% a s e MW N; w FY b a m E Patented Feb. 3, 1931 All;

warren STATES PATENT orrice ERNST w. annxalvnnnsoiv, or SCHENEGTADY, NEW YORK, assrenon r0 GENERAL ELECTRIC COMPANY, Aconronarron or new YORK 1 RADIO SIGNALING SYSTEM I Application filed May 9,

. My present invention relates to antennae for radio signaling systems- It is an ob ect of my nvention to provide conductor or a multiplicity of vertical con-.

ductors. T he horizontal portions of such antennae systems arenot usually employed-to produce radiationr-In the T antenna, for

example, the horizontal currents are opposing at any one time and. any tendency to radiate is therefore neutralized, while in the multiple tuned antennasimilar conditions occur. In the L antenna, while it is conceivable that the horizontal portion may produce a radiation, the proportion ofantenna height to wave length radiated is suchthat the radiation from the horizontal portion 1s either attenuation of a wave. One of'these factors is distance, i. e., the attenuation of a wave directly proportional to the distance travcl .ed by the wave.

portional to the distance travelled by. the

wave if this type of attenuation were the. only one with which we had to deal. 7'

, It has recently been established by various'observers that awave may be pro ected into space at a high angle over the horizon,

4., and that such a wave apparently travels in the upper stratas of the atmospheresuffering less attenuation than would be indicated by the Austin formula. The theory has thus become-accepted that there are two forms of wave propagation, one being the earth bound In accordance, with. this formula there are two factors which determine. the

In other words, the any plitude of the wave would be inversely pro- 1925. Serial No 29,210.

wave with high attenuation, and the other a space wavewith lower attenuation. I

The, new type of radiation which I have discovered belongs to the classof radiation which may be characterized as high angle or space radiation. I have found, however,

that it has different characteristics fromthe hi 'h angle space radiation that has been observed heretofore. This may be explained on the ground that the radiation of either the earth bound type or the high angle typeheretofore observed is vertically polarized, whereas the new type which I have discovcred is horizontally polarized, Byliorizontally polarized radiation I mean to indicate radiation in which the electrostatic oscillations are in a horizontal plane and the mag netic oscillations in a vertical plane.

/Vhile the vertically polarized high angle radiation which has been observed by others has been known to travel long distances with a low absorption, I have found that a portion of this radiation returns to earth withina short distance of the station and produces aresponse or interference in ordinary receiving sets. I have found, on the other hand, that horizontal polarized waves produce practically no impression on receiving sets adjacent the transmitting station or within a wide range of'the transmitter, while at a still greaterdistance the signals produced by the horizontally polarized 0 radiation are strongerfthanthe signals produced by the vertically polarized radiation of the same power. XV hen the horizontally polarizedradiation is received at a long distance from the transmitting station it has the same char plane of polarization .so thatafter having travelled a great distance it becomes a vertically polarized wave.

A horizontal conductor carrying oscillat ing currents and mounted at'a height over the" acteristics as the ordinary vertically polar ized radiation. This may be due to the fact that the wave which started in thehorizontal plane of polarization gradually changes its dinary waves.

radiation. two horizontal radiating conductors adapted The radiation produced by this radiator proceeds Vertically upwards and atvarious angles over the horizon, and any radiation that would occur parallel to the earth is short circuited by the earth. The radiation, however, that proceeds at an angle of 45 over the horizon probably produces the greatest effect.

Radiation from a horizontal radiator as above described has been measured at various distances from the transmitting station, and compared with similar measurements of or- For horizontally polarized waves these measurements show a field intensity in the neighborhood of the station which is practically zero. At a distance of fifteen kilometers (300 wave lengths) from the station the wave was found to be two thirds as strong as the ordinary or vertically polarized wave, whereas at 300 kilometers (6000 wave lengths) from the station the horizontally polarized wave was twice as. strong as the ordinarywave.

A horizontal radiator as above descr bed also produces high angle radiation in the direction of its own length. The longitudinal radiation proceeding at a 45 angle over the,

horizon. shows characteristics intermediate the purely horizontally polarized and the purely vertically polarized radiation. Thus it has been found that at a very short distance fromthe transmitting station the longitudinal radiation from a horizontal radiator is tical radiator whereas at right angles from the horizontal radiator the signals are still much weaker than the signals from the vertical radiator.

The above discoveries have led me to design an antenna system for communication over long distances which creates practically no signals or interference in the neighborhood of the station- The novel'features which I believe to be characteristic of my invention are set forth with particularity inthe appended claims. My invention'itself, however, both as to its organization and method of operationtogether with further objects and advantages thereof will best begunderstood by reference to the following description taken in connection with the accompanying drawing in which Fig. 1 shows diagrammatically an antenna whereby horizontally polarized waves may be produced. 7 Fig. 2 shows dia rammaticall a tuned loo radiator adaptedto produce horizontally polarized Fig. 3 shows diagrammatically to produce horizonta'll solarized radiation 1 Y 111 comoinatlon wlth phase shifting devices for controlling the direction of the radiated beam. Figs. 4 to 12, inclusive, show diagrammatically modifications of the radiators shown in Figs. 1 to 3 inclusive, each modification being adapted to produce horizontally polarized waves.

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lating currents by means of a source 3 and a transformer 4:. At any given instant the current in radiator 1 is in one direction'only. The current in the connecting or transmission lines 5 and 6 however always flows in opposite directions as indicated by the arrows thus providing a non-radiating connection between the'source of current 3 and the radiator 1. Vith a radiator of the type disclosed in Fig. 1, response registered by an ordinary rcceiverset in the neighborhood of the transmitter is practically negligible, although a strong response is produced at greater dis tances. A radiator ofthe simple type shown in this figure, however, is not very directive.

In Fig. 2 I have shown a loop antenna- 7 tuned by condensers '8. Thecondensers are so spaced that the series capacities neutralize the series inductances. Each side of the loop has a length equal to about one quarter of a wave length of the Wave'to be radiated, al-

though the lengths of thesides may be equalv to one halfa wave length if desired. The

current is introduced through the end of the a loop by means of non-radiating transmission lines9 and 10.. The upper portion ofthe loop is mounted above the earth a distance equal to at least one quarter ofa Wave length of the waveito be radiated. The lower portion of the loop may therefore bevery close to the earth. With this type of radiator it is possiof a wave length but less than one quarter of a-wave lengthof the radiated wave. When condensers arespaced apart a distance greater than one quarter, of a wave length of the ,wave to be radiated the antenna will have more than one degree of freedom, i. e. it may have more thanone system of oscillations at that frequency or closely adjacent frequentions confined to one system at that frequency or closely ad acent frequencies.

In the form of my invention shown in Fig. 3 I have indicated an antenna comprising a combination of two radiators 11 and 12 of the type disclosed in Fig. 1, both radiators being fed at the middle pointwith case if the currents in the two radiators are high frequency current from a source 3 and transformers 13 and 14: and through nonradiating transmission lines 1516 and 17-18. The radiators are spaced between centers about one half a wave length'of the wave to be radiated, and each radiator is approximately one half a wave length in extent. sion-lines are phase shifting devices 19 and 20 which control the phase relation in the currents of the two radiators. By varying the" phase relation of the currents in radiators 11 and 12 the direction-of radiation may be controlled. Thus, if the currents in the two radiators flow simultaneously in the be a maximum upwards and at right. angles H to the direction of theradiator. It,'onthe' 1 same direction the combined radiation will other hand, the currents inthe two radiators are of opposite phase, the radiation will be a maximum in a direction 45 upwards in the length direction of the radiators. The radiators are mounted above the earth a distance equal to, at least, one eighth of a'wave 7 disclosed in Fig. 2 and tuned by condensers 23. The sides of the loops vary in length from one quarter to one half a wavelength of I j I V square horizontal loop radiator 32 fed by non-radiating transmission lines. As'in the the wave to be radiated: The uppe-rside of the loop should, at least, be one quarter of a equals substantially one half a wave length lm-lengthrf'rom one quarter to one half the of the wave to be radiated, the resulting radiation from the vertical sides of the loop is neutralized in all directions, and all radiation takes place from the upper horizontal.

conductors. The directive characteristics of the resulting radiation depends, as in Fig. 3,

on the phase relation of the currents in the two loops. Phase shifting devices 24 and 25 control the phase relation of the currentsin the two loops and high frequency current is supplied to the radiators through fnonradiating transmission llIlQS.

Associated with each pair of transmisl V the rZtCllZLtOISllOWIl in Fig. 1- The radiator opposite and parallel to each other, and fed by non-radiating transmission lines. The distance between the suspending insulators 2 and the distance betweenflthe two radiators is approximately one half. a wave length of the wave to be radiated. The radiators are mounted above the earth a distance equal to at least one eighth of a wave length of the wave to be radiated. As in Figs; 3 and 4: phase shifting devices 28 and 29 control the phase of the current in the two radiators. In this modification of 30 of this figure is fed by non-radiating transmission lines, andhas a length equal to "one or more wave lengths; Seriescondensers 31, which are spaced apart 'a distance less than one quarter of a wavelength-,neutral ze the series inductances as in the caseof' the "loop radiator and c'on'iine the oscillations to one system at the frequency employed or closely acljacentfrequ'encies. The useofa plurality of condensers further serves to artificially prolong the length of the radiator and thus enable'a greater directive-effect to be obtained. The type of radiator shown in this figure will give ahigh angle horizontally polarized broadside" beam. As in the previous figures the antenna is inountedabove the earth a distance equal to at least one-eighth of a wave length of the wave to be radiated and issupplied with high frequency current through non-radiating transmission lines,

In Fig. 7 I have indicatedasubstantially previous figures, series capacity-j units 33, spaced apart a distance less than onequarter of'a wave length, neutralize the series induc tance's. Each side of the square may vary wave length of the wave to be 1 radiated. With, this type of radiator, horizontally polarized radiation, directed. to allpoints'of the compass, may be obtained. The eitect produced may be likened to a spray fountain. Theradiator is inounted abovethe earth, at least, one eighth of awave length of the wave to be radiated and is supplied through nonradiating transmission lines.

' The series tuned radiator34l shownin Fig. 3 is similar to that shown in Fig. 7 The length of the loop is 'onewave length or more, and the width approximately one quarter to 'one'halt'ofa wave length of the'wave to be radiated; I The condensers 35 associated with the loop'ne'utralize the seri esj inductances' and are spaced apart less than one quarter of a wave length. As in the previous figures the loop is fed with current. through nonrad1a t ing' transmission llnes. This type of radia tor gives a horizontally polarized high angle broadsidebeam.

Fig. 9 shows a radiator 36 similar to that shown in F ig.g6 in combination with a re- .flector 87. "The radiator and reflector each Fig. -shows a further modification of an antenna providing horizontally polarized.

waves. In this figure the radiators 39 and 40 are substantially identical with the radiator shown in Fig. 6. As in the previous figures condensers 41 are spaced apart less than one quarter of a wavelength. The distancebetween the radiators and the phase of the currents in the two radiators may be adjusted as desired to give the desired angle of elevation of the horizontally polarized radiation.

be connected in'series as shown in Figs. 9

Each radiator has a length equal to at least one wave length of the wave to be radiated and is supplied through non-radiating transmission'lines. Phase shifting devices 42 and 43 are associated with the transmission lines.

justment of the currents in the radiators may.

be made as in the previous cases by phase adjusting means 48, 49 and .50.

Fig. 12 shows a further modification of a loop antenna. figure. is similar to that shown in Fig. 8 but is adapted to be swung into various positions as indicated by the dotted lines 52 and 53. The direction of-the' radiated beam may be controlled by varying the position of the antenna. As in Fig. 8 the length of the antenna is one wave length or more. The neutralizing condensers 54 are spaced less than one quarter of a wave length apart and the horizontal portion of the radiator is fed through non-radiating transmission lines as in the other figures. The distance between the horizontal portions of the radiator may be from I one quarter to one half a wave length as desired. Y

In the case of horizonal radiators such as shown in Figs. 1, 3 and 5 to 11, inclusive, the

radiators are mounted at a distance above the earth equal to approximately one quarter 7.

The antenna 51 shown in the of a wave length of the wave to be radiated. Theheight may vary but should be at least one eighth of a wave length of the wave to be radiated. The radiator in each modification shown on the drawing is fed from a high frequency source through non-radiating transmission lines. While I have shown a current source comprising a high frequency alternator and a transformer, various other arrangements for supplying high frequency currents to the radiators may be employed if desired. I

, With vertical loop radiators as shown in Figs. 2 and 4, and with the type of loop radiator shown in Fig. 12 the upper horizontal portion of the loop may be one quarter of a wave length above the earth, and the lower portion of the loop may be very close to the earth.

Where a plurality of parallel conductors are employed the distance between the conductors may be varied or adjusted so as to control the direction of the radiated waves or beam. Instead of feeding. a plurality of parallelconductors from' a plurality of trans mission lines the conductors may, if desired,

and 12 and fed from a single pair of transmission lines. I

If desired, I may insert condensers or other devices in the transmission lines connecting the high frequency source with the radiators to prevent undesired oscillations which might occur in these lines and-generate vertically polarized waves.

Various modifications will readily suggest themselves to persons skilled in the art without departing from the scope of my inventlonas set forth in the appended claims.

- What I claim as new and desire'to secure by Letters Patent of the United States, is 1. An antenna comprising a radiating loop having its sides in asubstantially horizontal plane, said horizontal sides having a length equal to at least-a quarter of a wave length of the radiated wave, whereby horizontally polarized waves are produced, and said antenna beingmounted above the earth a dis tance equal to at least one eighth of a wave length of the wave to be radiated, andmeans' for supplying high frequency currentto said oop. I

2. A series tuned loop antenna arranged in a substantlally horizontal plane and at a distance above the earth *reater than one-eighth of the wave length of the wave to which said antenna is tuned and said antenna having a horizontal dimension of at least a quarter of a. wave length of the wave towhich the an tenna is tuned. 1

3.3An antenna system comprising a plurality of parallel conductors arranged in a horizontal plane, said conductors being electrically disconnected from the earth, means.

for supplying high frequency current to said conductors and means for controlling the phase relation of the current in different-com ductors thereby to control the direction of the radiated Waves. y

In Witness whereof, I have hereunto set my hand this 8th day of May, 1925.

ERNST F. WV. ALEXANDERSON.- 

